Host header poisoning

Some parts of Django -- independent of end-user-written applications
-- make use of full URLs, including domain name, which are generated
from the HTTP Host header. Some attacks against this are beyond
Django's ability to control, and require the web server to be properly
configured; Django's documentation has for some time contained
notes advising users on such configuration.

Django's own built-in parsing of the Host header is, however, still
vulnerable, as was reported to us recently. The Host header parsing in
Django 1.3 and Django 1.4 -- specifically,
django.http.HttpRequest.get_host() -- was incorrectly handling
username/password information in the header. Thus, for example, the
following Host header would be accepted by Django when running on
"validsite.com":

Host: validsite.com:random@evilsite.com

Using this, an attacker can cause parts of Django -- particularly the
password-reset mechanism -- to generate and display arbitrary URLs to
users.

To remedy this, the parsing in HttpRequest.get_host() is being
modified; Host headers which contain potentially dangerous content
(such as username/password pairs) now raise the exception
django.core.exceptions.SuspiciousOperation.

Documentation of HttpOnly cookie option

As of Django 1.4, session cookies are always sent with the HttpOnly
flag, which provides some additional protection from cross-site
scripting attacks by denying client-side scripts access to the session
cookie.

Though not directly a security issue in Django, it has been reported
that the Django 1.4 documentation incorrectly described this change,
by claiming that this was now the default for all cookies set by
the HttpResponse.set_cookie() method.

The Django documentation has been updated to reflect that this only
applies to the session cookie. Users of Django are encouraged to
review their use of set_cookie() to ensure that
the HttpOnly flag is being set or unset
appropriately.

Affected versions

The Host header issue described above is present in the
following versions of Django:

Django 1.3 release series (all versions)

Django 1.4 release series (all versions)

Django master development branch (soon to become Django 1.5)

The HttpOnly cookie documentation issue is present in
the following versions of Django:

Django 1.4 release series (all versions)

Django master development branch

Resolution

Patches have been applied to Django's development master branch,
and to the 1.4 and 1.3 release branches, which resolve the issues
described above. The patches may be obtained directly from the
following changesets:

Development master branch: commit for
the Host header issue and commit for
the HttpOnly cookie documentation issue.

Django 1.4: commit for
the Host header issue and commit for
the HttpOnly cookie documentation issue.

As Django's development branch is currently in a pre-alpha state,
users are strongly advised not to be running production deployments
from it; if you are currently doing so, however, you are urged to
upgrade imediately to the latest HEAD, which contains the above
patches.

Credits

The Host header issue was reported by James
Kettle. The HttpOnly cookie documentation issue was
reported by Preston Holmes, who is now a committer on Django.

General notes regarding security reporting

As always, we ask that potential security issues be reported via
private email to security@djangoproject.com, and not via Django's Trac
instance or the django-developers list. Please
see our security
policies for further information.